Through substrate via semiconductor components and methods of formation thereof

ABSTRACT

A structure and method of forming through substrate vias in forming semiconductor components are described. In one embodiment, the invention describes a method of forming the through substrate via by filling an opening with a first fill material and depositing a first insulating layer over the first fill material, the first insulating layer not being deposited on sidewalls of the fill material in the opening, wherein sidewalls of the first insulating layer form a gap over the opening. The method further includes forming a void by sealing the opening using a second insulating layer.

This is a continuation application of U.S. application Ser. No.12/790,220, U.S. Pat. No. 8,399,936 entitled “Through Substrate ViaSemiconductor Components,” which was filed on May 28, 2010, which is adivisional application of U.S. application Ser. No. 12/135,059, U.S.Pat. No. 7,772,123, entitled “Through Substrate Via SemiconductorComponents,” which was filed on Jun. 6, 2008 and are both incorporatedherein by reference.

TECHNICAL FIELD

This invention relates generally to electronic devices, and moreparticularly to through substrate via semiconductor components.

BACKGROUND

One of the goals in the fabrication of electronic components is tominimize the size of various components. For example, it is desirablethat hand held devices such as cellular telephones and personal digitalassistants (PDAs) be as small as possible. To achieve this goal, thesemiconductor circuits that are included within the devices should be assmall as possible. One way of making these circuits smaller is to stackthe chips that carry the circuits.

A number of ways of interconnecting the chips within the stack areknown. For example, bond pads formed at the surface of each chip can bewire-bonded, either to a common substrate or to other chips in thestack. Another example is a so-called micro-bump 3D package, where eachchip includes a number of micro-bumps that are routed to a circuitboard, e.g., along an outer edge of the chip.

Yet another way of interconnecting chips within the stack is to usethrough-vias. Through-vias extend through the substrate therebyelectrically interconnecting circuits on various chips. Through-viainterconnections can provide advantages in terms of interconnect densitycompared to other technologies. In addition to applications in 3D chipstacking, through-via interconnections can be used to increaseperformance of RF and power devices by providing very low resistiveground contacts to wafer backside and advanced heat sink capability.However, introduction of such interconnects may introduce additionalchallenges.

The integration of chips in 3D brings forth a number of new challengesthat need to be addressed. Hence, what is needed in the art are improvedstructures and methods of producing structures for 3D chip integration.

SUMMARY OF THE INVENTION

These and other problems are generally solved or circumvented, andtechnical advantages are generally achieved, by embodiments of thepresent invention that provide through silicon vias and methods ofmanufacture thereof.

Embodiments of the invention include methods and structures for formingthrough substrate vias. In accordance with an embodiment, the inventiondescribes a method of forming the through substrate via by forming athrough substrate via by partially filling an opening with a first fillmaterial, and forming a first insulating layer over the fill materialthereby forming a gap over the opening. The method further comprisesforming a second insulating layer to close the gap thereby forming anenclosed cavity within the opening.

The foregoing has broadly outlined the features of embodiments of thepresent invention in order that the detailed description of theinvention that follows may be better understood. Additional features andadvantages of embodiments of the invention will be describedhereinafter, which form the subject of the claims of the invention. Itshould be appreciated by those skilled in the art that the conceptionand specific embodiments disclosed may be readily utilized as a basisfor modifying or designing other structures or processes for carryingout the same purposes of the present invention. It should also berealized by those skilled in the art that such equivalent constructionsdo not depart from the spirit and scope of the invention as set forth inthe appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention, and theadvantages thereof, reference is now made to the following descriptionstaken in conjunction with the accompanying drawings, in which:

FIG. 1, which includes FIGS. 1 a-1 d, illustrates a portion of asemiconductor component with a through substrate via comprising atailored void, wherein FIG. 1 a illustrates a cross sectional view, FIG.1 b illustrates a top cross sectional view, and FIGS. 1 c and 1 dillustrate magnified top cross sectional views, in accordance withembodiments of the invention;

FIG. 2, which includes FIGS. 2 a and 2 b, illustrates a portion of asemiconductor component with a through substrate via comprising atailored void, wherein FIG. 2 a illustrates a cross sectional view andFIG. 2 b illustrates a top cross sectional view, in accordance withembodiments of the invention;

FIG. 3, which includes FIGS. 3 a-3 i, illustrates a method ofmanufacturing a through substrate via chip, according to embodiments ofthe invention;

FIG. 4 is a flow chart of a method of forming the through substrate viachip according to an embodiment of the invention;

FIG. 5, which includes FIGS. 5 a-5 e, illustrates a method ofmanufacturing a through substrate via chip according to embodiments ofthe invention;

FIG. 6 is a flow chart of a method of forming the through substrate viachip according to an embodiment of the invention;

FIG. 7, which includes FIGS. 7 a-7 d, illustrates a method ofmanufacturing a through substrate via chip according to embodiments ofthe invention; and

FIG. 8 is a flow chart of a method of forming the through substrate viachip according to an embodiment of the invention.

Corresponding numerals and symbols in the different figures generallyrefer to corresponding parts unless otherwise indicated. The figures aredrawn to clearly illustrate the relevant aspects of the embodiments andare not necessarily drawn to scale.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The making and using of the presently preferred embodiments arediscussed in detail below. It should be appreciated, however, that thepresent invention provides many applicable inventive concepts that canbe embodied in a wide variety of specific contexts. The specificembodiments discussed are merely illustrative of specific ways to makeand use the invention, and do not limit the scope of the invention.

The present invention will be described with respect to preferredembodiments in a specific context, namely partially filled throughsubstrate vias. The invention may also be applied, however, to othersemiconductor components comprising, for example, multiple chips and/orin forming voids or micro-voids in other components. One of ordinaryskill in the art will be able to recognize further examples as well.

Embodiments of the present invention utilize through substrate vias tocreate 3D chip packages. Stacking chips on top of one another provides ameans to achieve density, increased functionality, and/or additionalperformance. One way to realize the full benefits of chip stacking is toconnect the chips using deep, or through substrate vias. These viasextend from the active circuitry at one face of the chip to a bottomsurface of the chip. However, forming through substrate vias ischallenging not only during the fabrication of these through substratevias but also during subsequent processing and/or product lifetime.

One of the key problems associated with stacking such devices arisesfrom yield loss arising from stress induced failure of the product. Invarious embodiments, the present invention overcomes these limitationsby forming through substrate vias comprising voids that are tailored tominimize stress concentration.

A significant difference in coefficient of thermal expansion between thesubstrate and the fill material in a through substrate via can createlarge stress concentration around the through substrate via, forexample, during subsequent thermal processing. Such increased stress canresult in significant yield loss arising from cracks, de-lamination, viacollapse, as well as dislocations, stacking faults in the substrate,etc. Metals typically expand faster than silicon thus creating regionsof high compressive stress in the substrate as well as inside the fillmaterial.

In various embodiments, the present invention overcomes these problemsby reducing stress around the through substrate via by filling thethrough substrate via with an effective material with minimal thermalexpansion. In various embodiments, the effective material comprises acombination of metal and voids. For example, metals typically expandfaster than silicon, whereas voids, for example, filled with a gashaving negligible expansion relative to the silicon substrate. Hence, acombination of metal with voids produces an effective material with acoefficient of expansion comparable to the substrate. In one embodiment,this effective material comprises a void tailored to specific dimensionsand shape, the void forming an inner core region of the throughsubstrate via, while a conductive fill material forms an outer layer ofthe through substrate via.

Structural embodiments of the invention will be first described usingFIGS. 1-2. Various embodiments of the method of fabrication will then bedescribed using the flow charts of FIGS. 4, 6 and 8, and FIGS. 3, 5 and7.

An embodiment of the invention is illustrated in FIG. 1. FIG. 1 aillustrates a cross sectional view of a through substrate via, FIG. 1 billustrates a top cross sectional view of the through substrate via, andFIGS. 1 c and 1 d illustrate magnified top cross sectional views of thethrough substrate via.

Referring to FIG. 1 a, the substrate 10 comprises a top surface 13 and alower surface 16. The active regions 11 are disposed on the top surface13 and comprise devices such as transistors, resistors, capacitors,diodes, etc. (not shown). Metallization levels are disposed over the topsurface 13 of the substrate 10.

A inter level dielectric (ILD) layer 20 is disposed above the substrate10. In one embodiment, the ILD layer 20 comprises a silicon glass layersuch as a BPSG layer. In another embodiment, the ILD layer 20 comprisingmultiple dielectric layers is disposed above the substrate 10. The ILDlayer 20 comprises multi level metallization and forms the back end ofthe line circuitry.

A through substrate via 1 formed by filling a through substrate opening250 with a fill material 50 is disposed inside the substrate 10. Thethrough substrate opening 250 comprises a high aspect ratio opening inthe substrate. In various embodiments, the depth of the throughsubstrate opening 250 is around 50-150 um, while the diameter of thethrough substrate opening 250 is around 5-15 um. In various embodiments,the aspect ratio of the through substrate opening 250 is about 1:5 toabout 1:20. The through substrate via 1 is electrically coupled to thesubstrate, for example, through electrical metal lines, for example,metal line 19 disposed above the substrate 10.

A first insulating layer 30 is disposed over the ILD layer 20 and formsthe sidewalls of the through substrate opening 250. The first insulatinglayer 30, in one embodiment, comprises a nitride layer.

The through substrate opening 250 is lined with a sidewall liner 35 thatprovides electrical as well as mechanical insulation and support. Forexample, the outer layer of the sidewall liner 35 comprises a dielectriclayer to electrically insulate the active regions 11 from the throughsubstrate via 1. Further, a trench metal liner is disposed over theouter dielectric layer 31. In various embodiments, for example, inapplications in which the through substrate interconnect forms a groundcontact, the outer dielectric layer 31 is skipped. Hence, in suchembodiments, the trench metal liner is directly disposed on the sidewallof the through substrate opening 250. In various embodiments, asillustrated in FIG. 1 c, the trench metal liner comprises multipleliners. A first metal liner 32 forms a metal diffusion barrier. Examplesof the first metal liner 32 comprise a Ti/TiN layer. A second metalliner 34 comprises a low resistive metal liner such as a tungsten liner.The low resistive metal liner helps to minimize variations during theelectroplating process due to resistive loss. A third metal liner 36comprising a copper barrier is disposed over the second liner. The thirdmetal liner 36, in various embodiments, comprises a TaN layer followedby a Ta layer. A fourth metal liner 38 is disposed over the third metalliner 36. The fourth metal liner 38 comprises a thickness of about 200to about 500 nm. In various embodiments, the fourth metal liner 38comprises copper and forms the seed layer.

A fill material 50 partially fills the through substrate opening 250.The fill material 50 covers a part of the through substrate opening 250,leaving a tailored void 90 in the through substrate opening 250. A firstdielectric liner 41 is disposed on the sidewalls and bottom surface ofthe fill material 50. The first dielectric liner 41, in one embodiment,comprises a nitride layer. The first dielectric liner 41 in variousembodiments comprises a thickness of about 200 nm to about 500 nm, forexample, about 400 nm in one embodiment.

A second dielectric liner 42 is disposed over the first dielectric liner41. The second dielectric liner 42, in various embodiments, comprises athickness of about 20 nm to about 150 nm, for example, about 100 nm inone embodiment. In one embodiment, the second dielectric liner 42comprises a carbon comprising layer, for example, a pyrolytic carbonlayer. In other embodiments, other suitable materials that are harder topolish relative to the second dielectric liner 42 can be used. Forexample, in some embodiments, the second dielectric liner 42 comprisesSiN, SiC, or Si.

A second insulating layer 60 is disposed on the corner or edges of thethrough substrate opening 250. The second insulating layer 60 isdisposed over the top sidewall of the second dielectric liner 42. Thesecond insulating layer 60, in one embodiment, comprises an oxidematerial, for example, an oxide formed using a plasma enhanced processusing silane.

A third insulating layer 70 is disposed over a top portion of thethrough substrate opening 250 and seals the through substrate opening250 forming a tailored void 90 or enclosed cavity. The third insulatinglayer 70 is preferably a high density plasma based material. In oneembodiment, the third insulating layer 70 comprises a high densityplasma based oxide. Although illustrated to fill a lower portion of thetailored void 90, in various embodiments, the third insulating layer 70only seals the top portion of the tailored void 90. In variousembodiments, the third insulating layer 70 is formed from a high densityprocess that forces the pinch-off point 71 (FIG. 3 f) to be loweredinside the silicon substrate.

A fourth insulating layer 80 is disposed above the third insulatinglayer 70. The fourth insulating layer 80 forms a protective barrier andin some embodiments comprises a nitride material.

In various embodiments, the size and shape of the tailored void 90 isadjusted to form a through substrate via with minimum defectivityarising from thermal or other stress related defects. Although, only onethrough substrate via 1 is illustrated, a through substrate via chip maycomprise more than one through substrate via 1.

As manufacturability is a key concern, in various embodiments, afterselecting suitable materials, the thickness of the fill material 50 isselected relative to the dimension of the tailored void 90. For example,a fraction of the fill material 50 (f_(FM)) may be identified based onthe materials selected. For example, in FIG. 1 b, this fraction of thefill material 50 (f_(FM)) is a ratio of thickness of the fill materialr_(FM) to the radius of the through substrate opening r_(TSV). Thefraction (f_(FM)) depends on the relative difference between thecoefficient of thermal expansions of silicon (α_(Si)), fill material 50(α_(FM)) and the tailored void (α_(V)) asf_(FM)=(α_(Si)−α_(V))/(α_(FM)−α_(V)). Assuming negligible expansion ofthe tailored void or α_(DM)≈0, the fraction f_(FM)=α_(Si)/α_(FM). Hence,if copper is the fill material, a suitable fraction is about 30% theradius of the through substrate opening 250 r_(TSV). In other words, apartial fill that covers about 15% of the sidewall of the trenchminimizes the stress from thermal expansion. In various embodiments,thicker fill material can be used as stress up to a certain criticallimit (e.g., critical shear stress) can be safely accommodated. Forexample, the stress produced during a small increase in temperature maynot be significant. Hence, in various embodiments, a numerical simulatoris used to design the shape of the voids. In such embodiments, asuitable thickness is calculated numerically to minimize, for example,stress concentrations during subsequent processing. In some embodiments,a more sophisticated analysis utilizing 2D or 3D simulations usingfinite element simulators determines the appropriate shape and structureof the tailored void 90 relative to the fill material 50. Such numericalcalculations can account for changes in stress in different regions, forexample, in the corners. Suitable metrics, such as Von Misses criterion,based on the stress tensor may be used to monitor the stress in thestructure.

A second structural embodiment is illustrated in FIG. 2, which includesFIGS. 2 a and 2 b. FIG. 2 a illustrates a cross sectional view and FIG.2 b illustrates a top view. Unlike the embodiment illustrated in FIG. 1,in this embodiment, the tailored void 90 is lined by the firstdielectric liner 41. Hence, unlike the prior embodiment, a secondinsulating layer 60 is also disposed above the first insulating layer30.

An embodiment of a method of fabrication of the through substrate via 1is illustrated using FIG. 3, which includes FIGS. 3 a-3 h, and the flowchart of FIG. 4.

Referring to FIG. 3 a, a through substrate opening 250 is fabricated ina substrate 10. The substrate 10 is typically a semiconductor wafer withactive device regions 11. The active device regions 11 or activecircuitry can include transistors, resistors, capacitors, inductors orother components used to form integrated circuits. For example, activeareas that include transistors (e.g., CMOS transistors) can be separatedfrom one another by isolation regions, e.g., shallow trench isolation.The active device regions are fabricated during the front end of theline processing.

Next, metallization is formed over the active device regions 11 toelectrically contact and interconnect the active device regions 11. Themetallization and active circuitry together form a complete functionalintegrated circuit. In other words, the electrical functions of the chipcan be performed by the interconnected active circuitry. In logicdevices, the metallization may include many layers (e.g., nine or more,of copper). In memory devices, such as DRAMs, the number of metal levelsmay be less and may be aluminum.

Referring to the flow chart of FIG. 4, the components formed during thefront-end process are interconnected by back end of line (BEOL)processing. During this process, contacts are made to the semiconductorbody and interconnected using metal lines and vias. As discussed above,modern integrated circuits incorporate many layers of vertically stackedmetal lines and vias (multilevel metallization) that interconnect thevarious components in the chip. In FIG. 3 a, the back end of the linelayer 20 comprising the multilevel metallization is formed over thesubstrate 10.

In various embodiments, the through substrate opening 250 is formedafter the front end of the line and the back end of the line processing.However, in some embodiments, the through substrate opening 250 isformed after the front end of the line but before forming the back endof the line layers.

Referring again to FIG. 3 a, a high density plasma process in an RFplasma chamber is used to form a through substrate opening 250 from thetop surface of the workpiece. In one embodiment, a highly anisotropicetch is used to form a through substrate opening 250 with a forwardtaper (top broader than bottom). In other embodiments, other types ofreactive ion etch processes may be used, including processes usingsimultaneous bottom etch and sidewall passivation. In one embodiment, anetch step is carried out using a fluorine based plasma. However,fluorine based etches are isotropic and result in non vertical trenchsidewalls. Hence, a deposition step is carried out by introducing apolymer producing gas into the plasma chamber. The polymer producing gasdeposits a polymer layer on the exposed sidewalls forming a temporaryetch stop layer. The polymer layer is not formed on the exposed bottomsurface of the trench due to the high energy of the impinging ions. Anypolymer deposited on the bottom surface of the trench is broken up bythe high energy of the impinging ion. The through substrate opening etchprocess is carried out in sequential etch and deposition steps. Avertical trench may thus be produced. For example, the fluorine etchstep may comprise an SF₆ etchant, whereas the polymer producing gas maycomprise C₄F₈. The etch and deposit steps may be repeated many number oftimes, e.g., about 100 times to about 500 times, to form the throughsubstrate opening 250. In other embodiments, other types of reaction ionetch processes may be used. The through substrate opening 250 after theetch step may comprise any suitable vertical shape such as cylindrical,annular, faceted, etc.

The through substrate opening 250 thus produced comprises a high aspectratio in the range from about 1:5 to about 1:20 . The top of the throughsubstrate opening 250 comprises a width of about 2 um to about 20 um.The angle of the taper varies such that the bottom width is narrowerthan the top width, and is in the range from about 90 to about 80degrees.

The through substrate opening 250 comprises a top wider section 251 formaking contacts and a thinner long stem section 252 in the substrate 10.In some embodiments, the top wider section 251 may be skipped, producinga through substrate opening 250 comprising only the long stem section252. Such an embodiment reduces the use of a masking step (for producingthe top wider section 251) and reduces the cost of the fabricationprocess.

A sidewall liner 35 is formed on the sidewalls of the through substrateopening 250. The sidewall liner 35 in various embodiments comprisesmultiple layers. An outer dielectric liner 31 is formed over thesidewalls of the through substrate opening 250 and forms the outer layerof the sidewall liner 35. The outer dielectric liner 31 electricallyinsulates the active regions 11 from the through substrate via 1 (to beformed). The outer dielectric liner 31 may comprise silicon oxide,silicon nitride, silicon oxynitride, SiC, SiCN, a dense or porous low kor ultra low k dielectric material, an organic material or polymer likeparylene, BCB, SiLK or others. In some embodiments, the outer dielectricliner 31 is anisotropically etched forming a sidewall spacer.Alternately, outer dielectric liner 31 is etched after the grinding andthinning processes that expose the bottom surface of the throughsubstrate opening 250.

A trench liner comprising multiple metal liners is deposited over theouter dielectric liner 31 (as illustrated in the magnified top view ofFIG. 1 c). The trench liner is ideally conformal or at least continuous,and may comprise a single layer or layer combination of Ta, TaN, W, WN,WCN, WSi, Ti, TiN, Ru as examples. The trench liner is used, forexample, as a barrier layer for preventing metal from diffusing into theunderlying substrate 10 and outer dielectric liner 31. In the describedembodiment, the trench liner comprises first, second, third and fourthmetal liners 32, 34, 36 and 38, although in other embodiments lower ormore levels of metal liners may be used. In embodiments used for powerand/or RF applications, the electrical insulation using sidewall liner35 is not required. In such embodiments, a conductive trench liner isdirectly formed on the sidewalls of the through substrate opening 250.Hence, as illustrated in the magnified top view of FIG. 1 d, thesidewall liner 35 does not comprise the outer dielectric liner 31.

Referring to FIG. 1 c, a first metal liner 32 is formed over the outerdielectric liner 31. The first metal liner 32 forms a metal diffusionbarrier. If the sidewall liner process is skipped as in application forRF applications, the first metal liner 32 forms an electrical contactwith the substrate 10 (FIG. 1 d). The first metal liner 32 is formedusing a chemical vapor deposition process or a plasma enhanced CVDprocess or a combination of both, although in other embodiments, otherprocesses may be used. In one embodiment, the first metal liner 32comprises a Ti/TiN layer. A 5-30 nm titanium layer is deposited followedby a deposition of about a 20-100 nm TiN layer.

A second metal liner 34 is formed over the first metal liner 32. Thesecond metal liner 34 comprises a material with a low resistivity, forexample, in one embodiment, comprises tungsten. The low resistive metalliner helps to minimize potential drop and hence reduce variationsduring the electroplating process. The second metal liner 34 isdeposited using a chemical vapor deposition process, although in otherembodiments, other processes such as plasma vapor deposition may beused. In various embodiments, the second metal liner 34 is deposited toa thickness of about 50 nm to about 150 nm.

A third metal liner 36 comprising a copper barrier is formed over thesecond metal liner 34. The third metal liner 36 is deposited to athickness of about 100 to about 150 nm. The third metal liner 36, invarious embodiments, comprises a TaN layer followed by a layer oftantalum. In one embodiment, the tantalum nitride layer is deposited toa thickness of about 20-50 nm and the tantalum layer is deposited to athickness of about 100-150 nm.

A fourth metal liner 38 is deposited over the third metal liner 36. Thefourth metal liner 38 is deposited using a plasma vapor depositionprocess and forms a seed layer for the electroplating process in someembodiments. The fourth metal liner 38 comprises a thickness of about200 to about 500 nm. In various embodiments, the fourth metal liner 38comprises copper. The sidewall liner 35 thus formed comprises the outerdielectric liner 31, the first, second, third and fourth metal liners32, 34, 36 and 38. In various embodiments, the fourth metal liner 38 maybe deposited conformally or at least continuously using, for example, ametal-organic CVD (MOCVD) process or a PVD process.

Referring next to FIG. 3 b, a fill material 50 is deposited into thethrough substrate opening 250. The fill material 50 is electroplatedover the fourth metal liner 38.

The fill material 50 comprises a conductive material, such as copper oralternatively, aluminum, tungsten, silver, gold or doped polysilicon. Invarious embodiments, the fill material 50 comprises copper. The fillmaterial 50 is deposited to fill only a part of the through substrateopening 250. In one embodiment, the fill material 50 is deposited to athickness of about 20% to about 30% the depth of the through substrateopening 250. Use of such a partial fill of the through substrate opening250 results in a corresponding decrease in the fill time, andconsequently increases the throughput of the process. The partial fillalso saves the use of the expensive fill material 50, and the powerintensive process of electroplating the fill material 50. Particularlyat high frequencies (e.g., above 1 GHz), the resistance of a fullyfilled via can be significantly higher than that of a partially filledvia due to skin effect. Due to a doubling of the total surface, thepartially filled via offers about twice the number of modes formicrowave wave propagation, providing a further advantage of reducingthe Ohmic resistance by almost half at high operational frequencies. Inone embodiment, the thickness of the fill material 50 is about 2 um toabout 5 um.

Referring next to FIG. 3 c, the top surface of the wafer is planarizedto expose the first insulating layer 30. In various embodiments, theplanarization process comprises a chemical mechanical polishing (CMP).The CMP process removes the fill material 50 and the underlying sidewallliner 35. After polishing through the fill material 50, the CMP processremoves the first, second, third and fourth metal liners 32, 34, 36 and38. In various embodiments, the polishing process stops on the firstinsulating layer 30. A post CMP clean is next performed to remove theslurry residuals from the open through substrate opening 250.

As illustrated next in FIG. 3 d, an etch stop liner is deposited overthe top surface of the through substrate opening 250. A first dielectricliner 41 is deposited on the sidewalls and bottom surface of the fillmaterial 50. The first dielectric liner 41 is deposited using a plasmaenhanced deposition process such as a PECVD process, although in otherembodiments, other suitable deposition processes may be used. The firstdielectric liner 41 comprises a nitride material, in one embodiment. Thefirst dielectric liner 41 comprises a thickness of about 200 nm to about500 nm, and about 400 nm in one embodiment. A second dielectric liner 42is deposited over the first dielectric liner 41. The second dielectricliner 42 comprises a thickness of about 50 nm to about 150 nm. Thesecond dielectric liner 42 comprises a carbon containing layer invarious embodiments. In one embodiment, the second dielectric liner 42comprises a pyrolytic carbon layer. In other embodiments, oxide CMP stoplayer such as SiN or SiC may be used as the second dielectric liner 42.As discussed below, the second dielectric liner 42 forms a protectivestop layer during the subsequent polishing process.

As illustrated in FIG. 3 e, a second insulating layer 60 is depositedover the second dielectric liner 42. The second insulating layer 60 isdeposited using a highly anisotropic deposition process, for example,accomplished by using a plasma process. Hence, the second insulatinglayer 60 deposits non-conformally and does not deposit along thesidewalls of the through substrate opening 250. The second insulatinglayer 60, in one embodiment, comprises an oxide layer formed fromoxidizing silane. The process conditions for the second insulating layer60 are chosen to form a gap ‘g’ in a top portion of the throughsubstrate opening 250. In various embodiments, the gap g is tailored tobe about 1 um to about 3 um. For example, in one embodiment, this gap‘g’ is about 2 um.

Referring next to FIG. 3 f, a third insulating layer 70 is depositedover the second insulating layer 60. In various embodiments, the thirdinsulating layer 70 is deposited using a process that deposits, forexample, ions at high velocity. Hence, in various embodiments, the thirdinsulating layer 70 is deposited using a plasma/plasma enhanced process.In one embodiment, a plasma enhanced chemical vapor deposition processis used to deposit an oxide layer. In another embodiment, a high densityplasma process is used to form the third insulating layer 70. The thirdinsulating layer 70 fills the gap ‘g’ and forms the tailored void 90. Invarious embodiments the pinch-off point 71 is within the throughsubstrate opening 250. This ensures that the tailored void 90 isprotected and the seal is not etched off during subsequent processing.In various embodiments, the third insulating layer 70 is an oxide layer.

Referring next to the FIG. 3 g, a polishing process is used to planarizethe third insulating layer 70. The polishing process, in variousembodiments, comprises a CMP process. The CMP process is stopped on thesecond dielectric layer and polishes and removes the third insulatinglayer 70 and the underlying second insulating layer 60.

As next illustrated in FIG. 3 h, a selective etch process is used toremove the second dielectric liner 42 and the underlying firstdielectric liner 41. For example, a carbon ash process is used to removea second dielectric liner 42 comprising carbon to expose the firstinsulating layer 30.

Referring to FIG. 3, a fourth insulating layer 80 is deposited over thefirst insulating layer 30. The fourth insulating layer 80 is alsodeposited over the third insulating layer 70. The fourth insulatinglayer 80 is deposited using a CVD process such as PECVD, and comprises anitride layer in various embodiments.

The substrate 10 is subsequently processed using conventional processingto form back end of the line metallization layer, bond pads and finalpassivation layers. In other embodiments, the through substrate via 1 isfabricated after fabricating the back end of the line metallizationlayer. In such embodiments, the through substrate via 1 is fabricatedeither before or after forming the bond pads. In some embodiments, thethrough substrate via 1 is fabricated before the active devices arefabricated in the front end of the line.

The substrate 10 is subsequently thinned exposing a lower surface bygrinding to a desired thickness. The typical thickness of the substrate10 after the thinning is about 10 μm to about 150 μm. In differentembodiments, the thinning may also be performed chemically or using aplasma. For example, a modified plasma etch may be used to thin thesilicon wafer from the back side. Such techniques have the additionaladvantage of not damaging the front side. The advantage of thinning thesemiconductor wafer (or semiconductor chip, if the semiconductor waferhas already been diced) is to shorten the length of the through-vias,which enhances the electric properties and creates a via with arelatively vertical sidewall.

An embodiment of a method of fabrication of the through substrate via 1is illustrated using FIG. 5, which includes FIGS. 5 a-5 e, and the flowchart of FIG. 6.

Referring to FIG. 5 a, the process follows the steps described in theprevious embodiment with respect to FIGS. 3 a-3 c. As next illustratedin FIG. 5 b, a first dielectric liner 41 is deposited over the sidewallsand the bottom surface of the through substrate opening 250. However,unlike the prior embodiment, a second dielectric liner 42 is notdeposited.

Referring next to FIGS. 5 c and 5 d, a third insulating layer 70 isdeposited and patterned. A second insulating layer 60 is deposited asdescribed with respect to FIG. 3 e. Next, a third insulating layer 70 isdeposited as described with respect to FIG. 3 f. However, unlike theprior embodiment, a separate lithography step is used to pattern thethird insulating layer 70. The third insulating layer 70 is patternedsuch that a region directly above the through substrate opening 250 thatis now filled by the third insulating layer 70 is not etched. Thepatterned third insulating layer 70 is polished, for example, using aCMP process. As illustrated in FIG. 5 e, a fourth insulating layer 80 isdeposited as described with respect to FIG. 3 i.

An embodiment of a method of fabrication of the through substrate via 1is illustrated using FIG. 7, which includes FIGS. 7 a-7 c, and the flowchart of FIG. 8.

The through substrate opening 250 is formed as described with respect toFIG. 3 a. Further, as illustrated in FIG. 7 a, and as described withrespect to FIG. 3 a, the sidewall liner 35 comprising the outerdielectric liner 31, the first, second, third and fourth metal liners32, 34, 36 and 38 are deposited conformally.

Referring to FIG. 7 b and as described in FIG. 3 b, a fill material 50is deposited to partially fill the through substrate opening 250. Invarious embodiments, the fill material 50 is deposited to form anoptimum shape that minimizes stress concentration regions.

In various embodiments, the fill material 50 is electroplated over thefourth metal liner 38. In conventional electroplating processes, thesuper-fill effect is maximized to fill the bottom trench without formingvoids. However, such structures with bottom fills produce high localstress regions 51 at the base of the through substrate opening 250during subsequent processing. In different embodiments, this is avoidedby tailoring the shape of the fill material 50 lining the throughsubstrate opening 250.

In one embodiment, the super-fill effect is reduced relative to otherconventional trench filling processes. Super-fill effect fills the highaspect ratio trenches or openings due to a preferential deposition onthe bottom surface, permitting the bottom surface to rise before thesidewalls close off. However, since only a partial fill of the trench isrequired in various embodiments, the super-fill effect is tailored toform a fill material 50 comprising a specific optimum shape. Forexample, the deposition rate on the bottom surface of the throughsubstrate opening 250 is reduced. In various embodiments, this isaccomplished by reducing the super-fill effect that concentratesaccelerators near the bottom surface during the electroplating process.

Optionally, as illustrated in FIG. 7 c, an additional anisotropic etchmay be performed in some embodiments to reduce the thickness of the fillmaterial 50 on the bottom surface of the openings 250. Subsequentprocessing proceeds as discussed with respect to FIGS. 3 c-3 i.Referring to FIG. 7 d, the tailored void 90 thus formed comprisesdimensions that are tailored to minimize stress concentration during,for example, subsequent thermal cycling. In other embodiments, othersuitable processes such as catalyst enhanced chemical vapor depositionmay also be used to form the fill material 50.

Although embodiments of the present invention and their advantages havebeen described in detail, it should be understood that various changes,substitutions and alterations can be made herein without departing fromthe spirit and scope of the invention as defined by the appended claims.For example, it will be readily understood by those skilled in the artthat many of the features, functions, processes, and materials describedherein may be varied while remaining within the scope of the presentinvention.

Moreover, the scope of the present application is not intended to belimited to the particular embodiments of the process, machine,manufacture, composition of matter, means, methods and steps describedin the specification. As one of ordinary skill in the art will readilyappreciate from the disclosure of the present invention, processes,machines, manufacture, compositions of matter, means, methods, or steps,presently existing or later to be developed, that perform substantiallythe same function or achieve substantially the same result as thecorresponding embodiments described herein may be utilized according tothe present invention. Accordingly, the appended claims are intended toinclude within their scope such processes, machines, manufacture,compositions of matter, means, methods, or steps.

What is claimed is:
 1. A method for forming a semiconductor component,comprising: partially filling an opening with a fill material; forming afirst insulating layer over the fill material so as to form a gap overthe opening; and closing the gap with an insulating material therebyforming an enclosed cavity within the opening.
 2. The method of claim 1,wherein the gap is closed by forming a second insulating layer.
 3. Themethod of claim 1, wherein closing the gap comprises performing a highdensity plasma process.
 4. The method of claim 1, wherein the insulatingmaterial that closes the gap is deposited by a high density plasmaprocess.
 5. The method of claim 1, wherein the insulating material thatcloses the gap comprises the same material as the first insulatinglayer.
 6. The method of claim 5, wherein the same material comprises anoxide.
 7. A method for forming a semiconductor component, comprising:partially filling an opening with a fill material; forming a firstinsulating layer over the fill material so as to form a gap over theopening; and performing an high density plasma process to close the gapthereby forming an enclosed cavity within the opening.
 8. The method ofclaim 7, wherein performing a high density plasma process comprisesperforming a deposition process to deposit a second insulating layer. 9.The method of claim 7, wherein the gap is closed by an insulatingmaterial, wherein the insulating material is the same material as thefirst insulating layer.
 10. The method of claim 9, wherein the samematerial comprises an oxide.
 11. A method for forming a semiconductorcomponent, comprising: partially filling an opening with a fillmaterial; forming a first insulating layer over the fill material so asto form a gap over the opening; and closing the gap with an insultingmaterial to forming an enclosed cavity within the opening, wherein theinsulating material that closes the gap and the first insulating layercomprise as oxide.
 12. The method of claim 11, wherein the gap is closedby forming a second insulating layer.
 13. The method of claim 11,wherein closing the gap comprises performing a high density plasmaprocess.
 14. The method of claim 11, wherein the insulating materialthat closes the gap is deposited by a high density plasma process.